The present invention relates to the field of heat exchange systems and more particularly, to heat exchange systems which utilize waste heat from conventional refrigeration circuits to heat a water supply or other liquid source.
Air conditioners and/or heat pumps, which are typically installed in a wide variety of residential dwellings and commercial establishments, tend to consume a substantial amount of energy relative to other typical appliances found in such premises.
A typical air conditioner circuit includes, in the following order, a compressor from which a heat carrier fluid, such as refrigerant, flows from an outlet thereof; an outdoor heat exchanger typically including an outdoor condenser wherein the refrigerant flows and an electric fan for blowing external air over condenser coils thereby causing the refrigerant to be in heat exchanger relationship with the external environment; an evaporator or other refrigerant expansion device; and an indoor heat exchanger comprising an indoor coil and an electric fan for circulating the interior air over the coil thereby bringing the interior air into heat exchange relationship with the refrigerant flowing through the coil. In the air conditioner, heat from the interior environment is absorbed by cooled refrigerant via the indoor heat exchanger and typically this "waste" heat is dissipated to the external environment by the outdoor heat exchanger.
In a heat pump, a reversing valve is connected to the compressor outlet in the above circuit so that the refrigerant flow outlined above may be reversed, as desired. When the heat pump is in a heating mode, the outdoor heat exchanger absorbs heat from the external environment and the indoor heat exchanger dissipates heat to the interior environment. When the heat pump is in an air conditioning mode, the reverse occurs, as described above.
There are many apparatus disclosed in the prior art which seek to utilize the waste heat generated by the typical air conditioner or heat pump in order to heat a water supply, such as water from a swimming pool or the hot water supply of a dwelling. By doing so, water heating energy costs are lowered and a valuable resource is conserved.
U.S. Pat. No. 3,498,072 issued Mar. 3, 1970 to R. C. Stiefel discloses a method by which the heat rejected from a water cooled heat pump may be utilized to heat the water of a swimming pool, including the step of using the swimming pool recirculating system to circulate the swimming pool water through the cooling jacket of the condenser of the heat pump.
U.S. Pat. No. 4,168,745 issued Sep. 25, 1979 to The American Equipment Systems Corporation discloses a heat exchanger comprising a refrigerator tube in coil form leading from the output side of a compressor and a water tube in coil form tapped from a source of water to be heated, the tubes being coiled together so that each coil of the water tube is interposed between a coil of the refrigerant tube, and vice versa. Inner and outer cylindrical sleeves are disposed within and around the coiled tubes thereby defining an annulus which enhances the heat transfer from the refrigerant tube to the water tube. A housing surrounds the coiled tubes and the sleeves, and sealed end caps are provided at each end of the exchanger.
U.S. Pat. No. 4,588,026 issued May 13, 1986 to Raytheon Company discloses a heat exchanger comprising a bundle of flexible tubes extended longitudinally and asymmetrically through a flexible tubing of larger diameter to form a tube-in-tube assembly which is wound helically into a coil of desired size. Opposing end portions of the coil are provided with suitable fittings for permitting independent connection of the outer tubing to one fluid source and the bundle of flexible tubes to another fluid source.
U.S. Pat. No. 4,907,418 issued Mar. 13, 1990 to Louis DeFrazio describes a swimming pool heating system wherein the refrigerant from an air conditioner is used to heat the pool water. The heat exchange occurs in a sealed tank which contains a central perforated cylinder through which the pool water flows and a refrigerant cooling coil that extends about the central cylinder. Warmed refrigerant from the air conditioner is caused to flow through the refrigerant cooling coil in the sealed tank.
U.S. Pat. No. 5,184,472 issued Feb. 9, 1993 to Pierre Guilbault et al. discloses an "add-on a heat pump" swimming pool heater comprising a refrigerant-to-water heat exchanger with a water flow control and associated piping, a water temperature control, a flow detecting device and a specialized control logic which is integrated to the heat pump control. The heat exchanger is connected on the refrigerant side to the outlet of the compressor of the heat pump circuit and to the inlet of the reversing valve.
One drawback with the swimming pool water heating systems described above is that the add-on water-refrigerant heat exchanger is usually installed between the outlet of the compressor and the external heat exchanger. Thus, the refrigerant is always pumped to flow through piping of the water-refrigerant heat exchanger, even when the pool water heating system is not operating and warmed refrigerant is cooled by the conventional fan-forced, air-cooled condenser of the air conditioner or heat pump. Hence, considering that the pool water does not circulate in the water-refrigerant heat exchanger but hot refrigerant does flow therethrough, any residual water located within the water-refrigerant heat exchanger will be heated to possibly very high temperatures. Such heating may cause scale, e.g. calcium carbonate and the like, to form on the heat exchanger pipes which will eventually cause them to clog.
In addition when a reversible heat pump is employed as the pool water heating source, as described in U.S. Pat. No. 5,184,472, in the heating mode, refrigerant must flow through the pool water-refrigerant heat exchanger, thereby unnecessarily heating the pool water and reducing the efficiency of the heat pump to warm the interior environment. Even in heat pump systems where the water is not flowing through the heat exchanger, heat will still be lost to the outdoor environment as evidenced by the fact that such units melt the snow around them.
Accordingly, means are sought for an improved refrigerant circuit to alleviate the deficiencies in the prior art.
It is an object of the present invention to provide an improved refrigerant circuit for an air conditioner or heat pump with water heating functions which avoids the deficiencies in the prior art.